In the case of in-the-ear hearing devices, components such as a microphone, amplifier or loudspeaker are integrated in a housing shell of an earmold piece, said housing shell being shaped to suit the auditory canal of the hearing device wearer. The housing shell is sealed on the front side with a front plate in which is arranged for example a microphone opening for allowing through the sound to be recorded.
In order to prevent the penetration of cerumen and moisture into the interior of the hearing device all openings, in particular the microphone opening, must be sealed with suitable sound-permeable media.
The utility model DE G 84 36 783 discloses a protective device for the penetration of cerumen consisting of perforated caps that can be attached to the sound exit nozzles either directly in an in-the-ear hearing device or to an earmold piece of a behind-the-ear hearing device that can be inserted into the ear.
The patent specification EP 0 310 866 A1 describes an apparatus for sealing openings in hearing devices or in earmold pieces for hearing devices, in particular openings in a front cover for sound entry, sound exit or aeration. The sealing apparatus cited comprises inter alia a cap that can be screwed on or snapped on. A microporous membrane of non-adhesive material can be inserted into the corresponding opening.
Front plates or front covers, also known as faceplates, are today normally cast in plastic or constructed from one or several plastics in a stereo lithography system. In the patent specification DE 10 2007 053 540.8 subsequently published by the applicant, such faceplates and associated housing modules and their manufacture are described.
U.S. Pat. No. 4,972,488 describes various protective caps for preventing the penetration of earwax into the acoustic output behind the receiver in an in-the-ear hearing device. The protective cap has several calotte-shaped flanges on its outside that engage with a notch in a housing shell and can thus produce a form fit.
Furthermore EP 1458217 A2 specifies an acoustic filter element that can be inserted into an acoustic output opening of a hearing device. A membrane made of plastic has a collar-shaped section with openings to allow sound to pass through, with said section being surrounded by a ring-shaped section.
Furthermore EP 1439733 A1 discloses a microphone protection system made of plastic and consisting of a ring with bars that run to its center and there connect with one another, with an opening being formed between the ring and the bars. An additional filter is provided in the vicinity of the openings of the microphone protection system.